I'm copy "trainhorn.wav" to C:\Program Files (x86)\MetaTrader - EXNESS\Sounds.
Why alert sound by "alert.wav" only ?
Remark "trainhorn.wav" = 28k
It should work. I tested with this indicator and it worked.
**playsound does not work in strategy tester.
***ps, if you're still having problems, install mt4 outside programs_files.
Thank you .